Posted on by Shannon Hall

Experts Question Claim Tunguska Meteorite May Have Come from Mars

Image credit:

In 1908 a blazing white line cut across the sky before exploding a few miles above the ground with a force one thousand times stronger than the nuclear blast that leveled Hiroshima, Japan.

The resulting shock wave felled trees across more than 800 square miles in the remote forests of Tunguska, Siberia.

For over 100 years, the exact origins of the Tunguska event have remained a mystery. Without any fragments or impact craters to study, astronomers have been left in the dark. That’s not to say that all kinds of extraordinary causes haven’t been invoked to explain the event. Various people have thought of everything from Earth colliding with a small black hole to the crash of a UFO.

Russian researchers claim they may finally have evidence that will dislodge all conspiracy theories, but that “may” is huge. A team of four believes they have recovered fragments of the object — the so-called Tunguska meteorite — and even think they are Martian in origin. The research, however, is being called into question.

In a detective-like manner, the team surveyed 100 years’ worth of research. The researchers read eyewitness reports and analyzed aerial photos of the location. They performed a systematic survey of the central region in the felled forest and analyzed exotic rocks and penetration funnels.

A schematic of the Tunguska event. Image Credit:
A schematic of the central region in the felled forest due to the Tunguska event. Image Credit: Anfinogenov et al.

Previously, numerous expeditions failed to recover any fragments that could be attributed conclusively to the long-sought Tunguska meteorite. But then Andrei Zlobin, of the Russian Academy of Sciences’ Vernadsky State Geological Museum, discovered three stones with possible traces of melting. He published the results in April 2013.

Zlobin’s discovery paper was received with skepticism and Universe Today covered the news immediately. A curious question arose quickly: why did it take so long for Zlobin to analyze his samples? The expedition took place in 1988, but it took 20 years before the three Tunguska candidates were nominated and another five years before Zlobin finished the paper.

By Zlobin’s admission, his discovery paper was only a preliminary study. He claimed he didn’t carry out a detailed chemical analysis of the rocks, which is necessary in order to reveal their true nature. Most field experts quickly dismissed the paper, feeling there was more work to be done before Zlobin could truly know if these rocks were fragments from the Tunguska meteor.

Today, new research is moving forward with an analysis of the rocks originally discovered by Zlobin. But an interesting new addition to the collection is a rock called “John’s Stone” — a large boulder discovered in July, 1972. While it’s mostly a dark gray now it was much lighter at the time of its discovery. “John’s Stone has an almond-like shape with one broken side,” lead author Dr. Yana Anfinogenov told Universe Today.

Now the skeptical reader might be asking the same question as before: why is there such a large time-lapse between the discovery of John’s Stone and the analysis presented here? (It’s interesting to note that while this elusive rock has been reviewed in the literature for over 40 years, this is the first time it has appeared in an English paper). Anfinogenov claimed that new data (especially concerning Martian geology) allowed for a much better analysis today than it did in recent years.

Photos (1972) of John's Stone and related findings. Image Credit:
Photos (1972) of John’s Stone and related findings. Image Credit: Anfinovenov et al.

“The ground near John’s Stone presents undeniable impact signs suggesting that the boulder hit the ground with a catastrophic speed,” Anfinogenov told Universe Today. It left a deep trace in the permafrost which allowed researchers to note its trajectory and landing velocity coincides with that of the incoming Tunguska meteorite.

John’s Stone also contains shear-fractured splinter fragments with glossy coatings, indicating the strong effect of heat generated when it entered our atmosphere. The research team attempted to reproduce those glossy coatings found on the splinters by heating another fragment of John’s Stone to 500 degrees Celsius. The experiment was not successful as the fragment disintegrated in high heat.

“The authors do not present a strong case that the boulder known as John’s Stone was involved in the Tunguska event, or that it originated from Mars,” said Dr. Phil Bland, a meteorite expert at Curtin University in Perth, Australia.

They claim the mineral structure and chemical composition of the rocks — a quartz-sandstone with grain sizes of 0.5 to 1.5 cm and rich in silica — match rocks found on Mars. But their paper lacks any microanalysis of the samples, or isotopic study.

While there is a strong case that an impact on Mars could easily eject rock fragments that would then hit the Earth, something doesn’t match up. “The physics of ejecting material from Mars into interplanetary space argues for fragments with diameters of one to two meters, not the 20 to 30 meter range that would be required for Tunguska,” Bland told Universe Today.

It seems as though planetary geologists will require a much stronger case than this to be truly convinced John’s Stone is the Tunguska meteorite, let alone from Mars.

The paper is currently under peer-review but is available for download here.

Posted on by Shannon Hall

New Technique Puts Exoplanets on the Scale

Meet Kepler-22b, an exoplanet with an Earth-like radius in the habitable zone of its host star. Unfortunately its mass remains unknown. Image Credit: NASA

Astronomers constantly probe the skies for the unexpected. They search for unforeseen bumps in their data — signaling an unknown planet orbiting a star, a new class of astronomical objects or even a new set of physical laws that will rewrite the old ones. They are willing to embrace new ideas that may replace the wisdom of years past.

But there’s one exception to the rule: the search for Earth 2.0. Here we don’t want to find the unexpected, but the expected. We want to find a planet so similar to our own, we can almost call it home.

While, we can’t exactly image these planets with great enough detail to see if one’s a water world with luscious green plants and civilizations, we can use indirect methods to find an “Earth-like” planet — a planet with a similar mass and radius to the Earth.

There’s only one problem: the current techniques to measure an exoplanet’s mass are limited. To date astronomers measure radial velocity — tiny wobbles in a star’s orbit as it’s tugged by the gravitational pull of its exoplanet — to derive the planet-to-star mass ratio.

But given that most exoplanets are detected via their transit signal — dips in light as a planet passes in front of its host star — wouldn’t it be great if we could measure its mass based on this method alone? Well, astronomers at MIT have found a way.

Graduate student Julien de Wit and MacArthur Fellow Sara Seager have developed a new technique for determining mass by using an exoplanet’s transit signal alone. When a planet transits, the star’s light passes through a thin layer of the planet’s atmosphere, which absorbs certain wavelengths of the star’s light. Once the starlight reaches Earth it will be imprinted with the chemical fingerprints of the atmosphere’s composition.

The so-called transmission spectrum allows astronomers to study the atmospheres of these alien worlds.

But here’s the key: a more massive planet can hold on to a thicker atmosphere. So in theory, a planet’s mass could be measured based on the atmosphere, or the transmission spectrum alone.

Of course there isn’t a one to one correlation or we would have figured this out long ago. The atmosphere’s extent also depends on its temperature and the weight of its molecules. Hydrogen is so light it slips away from an atmosphere more easily than, say, oxygen.

So de Wit worked from a standard equation describing scale height — the vertical distance over which the pressure of an atmosphere decreases. The extent to which pressure drops off depends on the planet’s temperature, the planet’s gravitational force (a.k.a. mass) and the atmosphere’s density.

According to basic algebra: knowing any three of these parameters will let us solve for the fourth. Therefore the planet’s gravitational force, or mass, can be derived from its atmospheric temperature, pressure profile and density — parameters that may be obtained in a transmission spectrum alone.

With the theoretical work behind them, de Wit and Seager used the hot Jupiter HD 189733b, with an already well-established mass, as a case study. Their calculations revealed the same mass measurement (1.15 times the mass of Jupiter) as that obtained by radial velocity measurements.

This new technique will be able to characterize the mass of exoplanets based on their transit data alone. While hot Jupiters remain the main target for the new technique, de Wit and Seager aim to describe Earth-like planets in the near future. With the launch of the James Webb Space Telescope scheduled for 2018, astronomers should be able to obtain the mass of much smaller worlds.

The paper has been published in Science Magazine and is now available for download in a much longer form here.

Posted on by Shannon Hall

Why People Resist the Notion of Climate Change

Image Credit: NASA

One of the most striking features of the climate change ‘debate’ is that it’s no longer a debate. Climate scientists around the world agree that climate change is very real — the Earth is warming up and we are the cause.

Yet while there is consensus even among the most reserved climate scientists, a portion of the public persistently disagrees. A recent Pew Research Center — an organization that provides information on demographic trends across the U.S. and the world — survey found that roughly four-in-ten Americans see climate change as a global threat. Climate scientists are racking their brains in an attempt to find out why.

Yale law professor Dan Kahan has done extensive research which reveals how our deep-rooted cultural dispositions might interfere with our perceptions of reality.

Why We Resist Climate Change

In 2010 Kahan led a study, “Cultural Cognition of Scientific Consensus,” which found that individuals tend to weigh evidence and credit experts differently based on cultural considerations. Psychological mechanisms allow individuals to selectively credit or dismiss evidence and experts, depending on whether the views presented match the dominant view of their group.

“There is an interdependence between people’s prior beliefs about risk and their exposure to and understanding of information,” Kahan told Universe Today. “People are motivated to search out information in a biased way. They look more for information that is consistent with their views than for information that is going to refute their views.”

Kahan’s study was administered online to 1,500 U.S. adults. Preliminary analyses wanted to determine if the public thought there was a scientific consensus regarding climate change and if there was a scientific consensus regarding human activity as the cause.

A majority — 55 percent — of the subjects reported their opinion that most scientists agree that global temperatures are rising, 12 percent believed most scientists do not find that global temperatures are rising, and 33 percent believed that scientists are divided on the topic. On whether or not human activity is the cause, 45 percent believed scientists agree that human activity is the cause, 15 percent believed scientists don’t think human activity is the cause, and 40 percent believed scientists are divided on the topic.

The public is generally not in a position to investigate the data for themselves or even read a scientific paper full of unfamiliar acronyms, plots and equations. Instead they turn to experts for assistance. Often times in determining who is credible, individuals will trust those who share similar world views and personal values. They tend to seek information congenial to their cultural predispositions.

For Kahan’s first experiment, the subjects read the biographical information of an expert scientist. They had to decide whether he was credible, having earned a Ph.D. from an elite university and now serving as a faculty member of another elite university. Those who listed themselves as hierarchical — believing in stratified social roles (generally conservatives) —  were more likely to find the expert scientist credible, while those who listed themselves as communitarian — expecting individuals to secure their own well-being (generally liberals) — were more likely to find the expert scientist not credible.

These fictional individuals were identified as credible or not based on their biographies only.
These fictional individuals were identified as credible or not based on their biographies only. Credit: Kahan et al. 2010

However, a second experiment showed the subjects not only the resume of the expert scientist but his position as well. Half the subjects were shown evidence that the expert believed in climate change, placing us at a high risk, while the other half of the subjects were shown evidence that the expert didn’t believe in climate change, placing us at a low risk.

The position imputed by the expert scientist dramatically affected the responses of the subjects. When the expert scientist supported a high risk position, 23 percent of the hierarchs and 88 percent of the communitarians found him credible. In contrast, when the expert scientist supported a low risk position, 86 percent of the hierarchs and 47 percent of the communitarians found him credible.

Whether the expert scientist was considered credible was highly associated with whether he took the position dominant in the subject’s cultural group. The subjects “have dispositions that are connected to their values that then will affect how they make sense of information,” Kahan said.

Image Credit: Kahan et al. 2010
The percentage of subjects who found the author credible depending on whether he supported a high risk (climate change is real) or low risk (climate change is not real) position. Credit: Kahan et al. 2010

At the end of the day the conclusion is simple: we’re human.  And this leads us to take the path of least resistance: we choose to believe in what those around us believe.

So it’s not that people aren’t sufficiently rational. “They’re too rational,” Kahan said. “They’re too good at extracting from the information you’re giving them, which sends the message that tells them what position they should take given the kind of person they are.”

Moving Forward

Kahan’s study shows that scientific consensus alone will not sway the public. The public will remain polarized despite efforts to increase trust in scientists or simply awareness of scientific research. Instead the key is to use science communication strategies, which reduce the likelihood the public will find climate change threatening.

In a more recent study, published in Nature, Kahan analyzed two techniques of science communication that may help break the connection between cultural predispositions and the evaluation of information.

The first technique is to frame the information in a manner that doesn’t threaten people’s values. In this study, Kahan and his colleagues asked participants to once again assess the credibility of climate change. But before doing so the subjects had to read an article.

One article was a study suggesting that carbon dissipates from the atmosphere much slower than scientists had previously thought. As a result, if we stopped producing carbon today, there would still be catastrophic effects: rising sea level, drought, hurricanes, etc. Another article (shown to a different group) gave information on geo-engineering or nuclear power — potential technological advances that may help reduce the effects of climate change. A final control group read an unrelated article on traffic lights.

Logically all of these articles had nothing to do with whether climate change is valid. But psychologically these articles did determine the meaning that people attached to the evidence of climate change. In all cases the hierarchs were less likely than the communitarians to say climate change is valid. But the gap was 29 percent smaller among the group that was first exposed to geo-engineering than the group that was exposed to regulating carbon.

“The evidence of whether there is a problem doesn’t depend on what you’re going to do about it,” Kahan said. “But psychologically it can make a difference.”

People tend to resist scientific evidence that may lead to restrictions on their personal activities, or evidence that threatens them as individuals  But if they are presented with information in a way that upholds their identities, they react with an open mind.

The second technique is to ensure that climate change is vouched for by a diverse set of experts. If a particular group is able to identify with that expert, then that group will be more open-minded in addressing the study. This will help reduce the initial polarization between hierarchs and communitarians.

Kahan argues that science “needs better marketing.” It needs to combine climate change with meanings that are affirming rather than threatening to people. When groups can identify with the expert, or are presented with possible solutions to climate change, the individuals in that group will stop attaching the issues to identity.

According to Kahan, in order to move forward, science communication needs to change the narrative. It needs to mitigate the connection between climate change and the individual. In order for there to be a public consensus on climate change it has to be presented in a less threatening manner.

This doesn’t mean that science communication has to avoid the nasty truth about climate change in order to finally reach a public consensus. Instead it has to spin climate change in a positive way — a way that is less threatening to the individual.

Science communication has to focus the public’s attention on what so many individuals value: efficiency, not being wasteful, innovation and moving forward. Only then will the public reach a consensus where there is now only polarization.

Posted on by Shannon Hall

High Potential for Life Circling Alpha Centauri B, our Nearest Neighbor

Image Credit: NASA

While exoplanets make the news on an almost daily basis, one of the biggest announcements occurred in 2012 when astronomers claimed the discovery of an Earth-like planet circling our nearest neighbor, Alpha Centauri B, a mere 4.3 light-years away. That’s almost close enough to touch.

Of course such a discovery has led to a heated debate over the last three years. While most astronomers remain skeptical of this planet’s presence and astronomers continue to study this system, computer simulations from 2008 actually showed the possibility of 11 Earth-like planets in the habitable zone of Alpha Centauri B.

Now, recent research suggests that five of these computer-simulated planets have a high potential for photosynthetic life.

The 2008 study calculated the likely number of planets around Alpha Centauri B by assuming an initial protoplanetary disk populated with 400 – 900 rocks, or protoplanets, roughly the size of the Moon. They then tracked the disk over the course of 200 million years through n-body simulations — models of how objects gravitationally interact with one another over time — in order to determine the total number of planets that would form from the disk.

While the number and type of exoplanets depended heavily on the initial conditions given to the protoplanetary disk, the eight computer simulations predicted the formation of 21 planets, 11 of which resided within the habitable zone of the star.

A second team of astronomers, led by Dr. Antolin Gonzalez of the Universidad Central de Las Villas in Cuba, took these computer simulations one step further by assessing the likelihood these planets are habitable or even contain photosynthetic life.

The team used multiple measures that asses the potential for life. The Earth Similarity index “is a multi-parameter first assessment of Earth-likeness for extrasolar planets,” Dr. Gonzalez told Universe Today. It predicts (on a scale from zero to one with zero meaning no similarity and one being identical to Earth) how Earth-like a planet is based on its surface temperature, escape velocity, mean radius and bulk density.

Planets with an Earth Similar index from 0.8 – 1 are considered capable of hosting life similar to Earth’s. As an example Mars has an Earth Similar index in the range of 0.6 – 0.8. It is thus too low to support life today.

However, the Earth Similarity index alone is not an objective measure of habitability, Gonzalez said. It assumes the Earth is the only planet capable of supporting life. The team also relied on the P model for biological productivity, which takes into account the planet’s surface temperature and the amount of carbon dioxide present.

At this point in time “there is no way to predict, at least approximately, the partial pressure of carbon dioxide with the known data, or the variations from a planet to another,” Gonzalez said. Instead “we assumed a constant partial pressure of carbon dioxide for all planets simplifying the model to a function of temperature.”

Gonzalez’s team found that of the 11 computer-simulated planets in the habitable zone, five planets are prone for photosynthetic life. Their Earth Similarity index values are 0.92, 0.93, 0.87, 0.91 and 0.86. If we take into account their corresponding P model values we find that two of them have better conditions than Earth for life.

According to this highly theoretical paper: if there are planets circling our nearest neighbor, they’re likely to be teeming with life. It’s important to note that while these indexes may prove to be very valuable years down the road (when we have a handful of Earth-like planets to study), we are currently only looking for life as we know it.

The paper has been published in the Cuban journal: Revista Cubana de Fisica and is available for download here. For more information on Alpha Centauri Bb please read a paper available here published in the Astrophysical Journal.

Posted on by Shannon Hall

Search for Planetary Nurseries in the Latest Citizen Science Project

Image Credit: diskdetectives.org

Growing up, my sister played video games and I read books. Now that she has a one-year-old daughter we constantly argue over how her little girl should spend her time. Should she read books in order to increase her vocabulary and stretch her imagination? Or should she play video games in order to strengthen her hand-eye coordination and train her mind to find patterns?

I like to believe that I did so well in school because of my initial unadorned love for books. But I might be about to lose that argument as gamers prove their value in science and more specifically astronomy.

Take a quick look through Zooniverse and you’ll be amazed by the number of Citizen Science projects. You can explore the surface of the moon in Moon Zoo, determine how galaxies form in Galaxy Zoo and search for Earth-like planets in Planet Hunters.

In 2011 two citizen scientists made big news when they discovered two exoplanet candidates — demonstrating that human pattern recognition can easily compliment the powerful computer algorithms created by the Kepler team.

But now we’re introducing yet another Citizen Science project: Disk Detective.

Planets form and grow within dusty circling planes of gas that surround young stars. However, there are many outstanding questions and details within this process that still elude us. The best way to better understand how planets form is to directly image nearby planetary nurseries. But first we have to find them.

zooniverse

“Through Disk Detective, volunteers will help the astronomical community discover new planetary nurseries that will become future targets for NASA’s Hubble Space Telescope and its successor, the James Webb Space Telescope,” said the chief scientist for NASA Goddard’s Sciences and Exploration Directorate, James Garvin, in a press release.

NASA’s Wide-field Infrared Survey Explorer (WISE) scanned the entire sky at infrared wavelengths for a year. It took detailed measurements of more than 745 million objects.

Astronomers have used complex computer algorithms to search this vast amount of data for objects that glow bright in the infrared. But now they’re calling on your help. Not only do planetary nurseries glow in the infrared but so do galaxies, interstellar dust clouds and asteroids.

While there’s likely to be thousands of planetary nurseries glowing bright in the data, we have to separate them from everything else. And the only way to do this is to inspect every single image by eye — a monumental challenge for any astronomer — hence the invention of Disk Detective.

Brief animations allow the user to help classify the object based on relatively simple criteria, such as whether or not the object is round or if there are multiple objects.

“Disk Detective’s simple and engaging interface allows volunteers from all over the world to participate in cutting-edge astronomy research that wouldn’t even be possible without their efforts,” said Laura Whyte, director of Citizen Science at the Adler Planetarium in Chicago, Ill.

The project is hoping to find two types of developing planetary environments, distinguished by their age. The first, known as a young stellar object disk is, well, young. It’s less than 5 million years old and contains large quantities of gas. The second, known as a debris disk, is older than 5 million years. It contains no gas but instead belts of rocky or icy debris similar to our very own asteroid and Kupier belts.

So what are you waiting for? Head to Disk Detective and help astronomers understand how complex worlds form in dusty disks of gas. The book will be there when you get back.

The original press release may be found here.

Posted on by Shannon Hall

Surprise! Fomalhaut’s Kid Sister Has a Debris Disk Too

Image Credit: Amanda Smith

The bright star Fomalhaut hosts a spectacular debris disk: a dusty circling plane of small objects where planets form. At a mere 25 light-years away, we’ve been able to pinpoint detailed features: from the warm disk close by to the further disk that is comparable to the Solar System’s Kuiper belt.

But Fomalhaut never ceases to surprise us. At first we discovered a planet, Fomalhaut b, which orbits in the clearing between the two disks. Then we discovered that Fomalhaut was not a single star or a double star, but a triplet.  The breaking news today, however, is that we have discovered a mini debris disk around the third star.

Fomalhaut is massive, weighing in at 1.9 times the mass of the Sun. And at such a close distance it’s one of the brightest stars in the southern sky. But its two companions are much smaller. The second star, Fomalhaut B, is 0.7 times the mass of the Sun and the third star, Fomalhaut C, a small red dwarf, is 0.2 times the mass of the Sun.

Fomalhaut C orbits Fomalhaut A at a distance of 2.5 light-years, or roughly half the distance from the Sun to the closest neighboring star.  It was only confirmed to be gravitationally bound to Fomalhaut A and Fomalhaut B in October of last year.

“The disk around Fomalhaut C was a complete surprise,” lead researcher Grant Kennedy of the University of Cambridge told Universe Today. “This is only the second system in which disks around two separate stars have been discovered.”

Relatively cool dust and ice particles are much brighter at long wavelengths, allowing telescopes like the Herschel Space Telescope, to pick up the excess infrared light. However, Herschel has a much poorer resolution than an optical telescope so the image of Fomalhaut C’s disk is not spatially resolved — meaning the brightness of the disk could be measured but not its structure.

Kennedy’s team’s best guess is that the disk is quite cold, around 24 degrees Kelvin and pretty small, orbiting to and extent of 10 times the distance from the Earth to the Sun. But it’s likely that it’s similar to Fomalhaut A’s disk in that it’s bright, elliptical, and slightly offset from its host star. All three characteristics suggest that gravitational perturbations may be destabilizing the cometary orbits within the disks.

“As a stellar system Fomalhaut’s gotten very interesting in the last year,” Kennedy said. With two wide companions “it’s not obvious how the configuration came about. Forming one wide companion is not so hard, but getting a second is very unlikely. So we need to come up with a new mechanism.”

Kennedy is currently working on figuring out what exactly this “new mechanism” is and he thinks the debris disk around Fomalhaut C will provide a few helpful hints. His best guess is still under construction but it’s likely that a small star is disturbing the system.

The next step will be to watch the stellar system over the next few years in order to measure their orbits exactly. With precise motions we just might be able to see what is interrupting the system.

“We think these observations will provide a good test of the theory,” Kennedy told Universe Today. They just might “solve the mystery of why the Fomalhaut system looks like it does.”

The paper has been published in the Monthly Notices of the Royal Astronomical Society and is available for download here.

Posted on by Shannon Hall

Enduring Quests and Daring Visions: NASA Lays Out a Roadmap for Astrophysics

An artist's concept of Kepler-69c, a super-Earth in the habitable zone of a sun-like star.

Three decades ago we were unaware that exoplanets circled other stars. We had just started talking about dark matter but remained blissfully ignorant of dark energy. The Hubble Space Telescope was still on the drawing board and our understanding of the life cycle of stars, the evolution of galaxies, and the history of the Universe was shaky.

But over the past three decades we have discovered thousands of exoplanets around other stars. We have mapped the life cycle of stars from their formation in beautiful stellar nurseries to their sometimes explosive deaths. We have seen deep into the history of the Universe allowing us to paint a picture of galaxies growing from mere shreds to the incredible spiral structures we see today. We now believe dark matter dominates the underlying framework of the Universe, while dark energy drives its accelerating expansion.

The amount of growth over the past three decades has been dramatic. To better access what the next three decades will bring, NASA has laid out a roadmap — a long-term vision for future missions — necessary to advance our understanding of the Universe.

In March 2013, the NASA Advisory Council/Science Committee assembled a group of astronomers who would determine the goals and aims of NASA for the next 30 years. The final product is this so-called roadmap officially titled “Enduring Quests Daring Visions — NASA Astrophysics in the Next Three Decades.”

The roadmap first notes three defining questions NASA should continue to pursue:
— Are we alone?
— How did we get here?
— How does the Universe work?

“Seeking answers to these age-old questions are enduring quests of humankind,” the roadmap states. “The coming decades will see giant strides forward in finding earthlike habitable worlds, in understanding the history of star and galaxy formation and evolution, and in teasing out the fundamental physics of the cosmos.”

In order to better address these questions, the roadmap defines three broad categories of time: the Near-Term Era, defined by missions that are currently flying or planned for this coming decade, the Formative Era, defined by missions that are designed and built in the 2020s, and the Visionary Era, defined by advanced missions for the 2030s and beyond.

Image Credit: NASA 2014
A schematic of the next 30 years subdivided into three decades across the entire electromagnetic spectrum. Image Credit: NASA 2014

Are we alone?

The Near-Term Era’s goal is to develop a comprehensive understanding of the demographics of planetary systems. The Kepler mission has already supplied a plethora of information on hot planets orbiting close to their parent stars. The WFIRST-AFTA mission — a wide-field infrared survey planned to launch in 2024 — will compliment this by supplying information on cold and free-floating planets.

The Formative Era’s goal is to characterize the surfaces and atmospheres of nearby stars. This will allow us to move beyond characterizing planets as Earth-like in mass and radius to truly being Earth-like in planetary and atmospheric composition. A proposed mission that allows a large star-planet contrast will directly measure oxygen, water vapor, and other molecules in the atmospheres of Earth-like exoplanets.

The Visionary Era’s goal is to produce the first resolved images of Earth-like planets around other stars. The roadmap team hopes to identify continents and oceans on distant worlds using optical telescopes orbiting hundreds of kilometers apart.

How did we get here?

The Near-Term Era will use the James Webb Space Telescope to supply unprecedented views of protostars and star clusters. It will resolve nearby stellar nurseries and take a closer look at the earliest galaxies.

The Formative Era will trace the origins of planets, stars and galaxies across a spectrum of wavelengths. An infrared surveyor will resolve protoplanetary disks while an X-ray surveyor will observe supernova remnants and trace how these incredible explosions affected the evolution of galaxies. Gravitational wave detectors will untangle the complicated dance between galaxies and the supermassive black holes at their centers.

The Visionary Era will peer nearly 14 billion years into the past when ultraviolet photons from the first generation of stars and black holes flooded spaced with enough energy to free electrons. The James Webb Space Telescope will provide an extraordinary means to better view this threshold.

How does the Universe work?

The Universe is full of extremes. Conditions created in the first nanoseconds of cosmic time and near the event horizons of black holes cannot be recreated in the lab. But the Near-Term and Formative Era’s goals will be to measure the cosmos with such precision that scientists can probe the underlying physics of cosmic inflation and determine the exact mechanisms driving today’s accelerating expansion.

The Visionary Era may use gravitational wave detectors to detect space-time ripples produced during the early stages of the Universe or map the shadow cast by a black hole’s event horizon.

The past 30 years have shown a dramatic growth in knowledge with unimaginable turns. Even with such a detailed framework laid out for the next 30 years, it’s likely that many missions are currently beyond the edge of the present imagination. The most exciting results will be drawn from the questions we haven’t even thought to ask yet.

And as with any of the recent “roadmaps” that the various divisions throughout NASA have presented, the biggest question will be if the funding will be available to make these missions a reality.

Again, this 110-page read may be found here.

The roadmap team consists of Chryssa Kouveliotou (NASA/MSFC), Eric Agol (University of Washington), Natalie Batalha (NASA/Ames), Jacob Bean (University of Chicago), Misty Bentz (Georgia State University), Neil Cornish (Montana State University), Alan Dressler (The Observatories of the Carnegie Institution for Science), Scott Gaudi (Ohio State University), Olivier Guyon (University of Arizona/Subaru Telescope), Dieter Hartmann (Clemson University), Enectali Figueroa-Feliciano (MIT), Jason Kalirai (STScI/Johns Hopkins University), Michael Niemack (Cornell University), Feryal Ozel (University of Arizona), Christopher Reynolds (University of Maryland), Aki Roberge (NASA/GSFC), Kartik Sheth (National Radio Astronomy Observatory/University of Virginia), Amber Straughn (NASA/GSFC), David Weinberg (Ohio State University), Jonas Zmuidzinas (Caltech/JPL), Brad Peterson (Ohio State University) and Joan Centrella (NASA Headquarters).

Posted on by Shannon Hall

Nearby Brown Dwarf System May Harbor Closest Exoplanet to Earth

WISE J104915.57-531906 as seen in NASA’s All-WISE survey (centered) and resolved to show its binary nature by the Gemini Observatory (inset). (Credit: NASA/JPL/Gemini Observatory/AURA/NSF).

In 2012 astronomers announced the discovery of an Earth-like planet circling our nearest neighbor, Alpha Centauri B, a mere 4.3 light-years away. But with such a discovery comes heated debate. A second group of astronomers was unable to confirm the exoplanet’s presence, keeping the argument unresolved to date.

But not to worry. One need only look 2.3 light-years further to see tantalizing — although yet unconfirmed — evidence of an exoplanet circling a pair of brown dwarfs: objects that aren’t massive enough to kick-off nuclear fusion in their cores. There just may be an exoplanet in the third closest system to our Sun.

Astronomers only discovered the system last year when the brown dwarfs were spotted in data from NASA’s Wide-field Infrared Explorer (WISE). Check out a past Universe Today article on the discovery here. They escaped detection for so long because they are located in the galactic plane, an area densely populated by stars, which are far brighter than the brown dwarfs.

Henri Boffin at the European Southern Observatory led a team of astronomers on a mission to learn more about these newly found dim neighbors.  The group used ESO’s Very Large Telescope (VLT) at Paranal in Chile to perform astrometry, a technique used to measure the position of the objects precisely. This crucial data would allow them to make a better estimate of the distance to the objects as well as their orbital period.

Boffin’s team was first able to constrain their masses, finding that one brown dwarf weighs in at 30 times the mass of Jupiter and the other weighs in at 50 times the mass of Jupiter. These light-weight objects orbit each other slowly, taking about 20 years.

But their orbits didn’t map out perfectly — there were slight disturbances, suggesting that something was tugging on these two brown dwarfs. The likely culprit? An exoplanet — at three times the weight of Jupiter — orbiting one or even both of the objects.

“The fact that we potentially found a planetary-mass companion around such a very nearby and binary system was a surprise,” Boffin told Universe Today.

The next step will be to monitor the system closely in order to verify the existence of a planetary-mass companion. With a full year’s worth of data it will be relatively straightforward to remove the signal caused by the exoplanet.

So far only eight exoplanets have been discovered around brown dwarfs. If confirmed, this planet will be the first to be discovered using astrometry.

“Once the companion is confirmed, this will be an ideal target to image using the upcoming SPHERE instrument on the VLT,” Boffin said. This instrument will allow astronomers to directly image planets close to their host star — a difficult technique worth the challenge as it reveals a wealth of information about the planet.

Once confirmed, this planet will stand as the closest exoplanet to the Sun, until the debate regarding Alpha Centauri Bb is resolved.

The paper has been accepted for publication as an Astronomy & Astrophysics Letter and is available for download here. For more information on Alpha Centauri Bb please read a paper available here and published in the Astrophysical Journal.

Posted on by Shannon Hall

Global Warming Explained in 52 Seconds

Graphic from "How Global Warming Works."

We are awash in the unseen, the unknown and the unexplained. Our Universe is enshrouded in mystery. Even what we do know — the complex physical laws that describe the planets, stars and galaxies — can seem just beyond any normal human being’s grasp. We can’t all be Einsteins, after all.

But excluding string theory, dark energy and quantum field theory most of science is remarkably within our grasp. And in less than a minute, a concept as culturally conflicted and misunderstood as global warming, can be explained. See above.

The motivation behind this video is simple. Research shows that virtually no Americans — roughly 0 percent — can explain the physical mechanisms of global warming at even a basic level. So Berkeley Professor Michael Ranney and colleagues created a total of five videos (with the longest clocking in at 656 words in under five minutes) with the hope of elucidating the basics of global warming.

Their initial study, completed in 2011, surveyed 270 people in San Diego parks in order to assess how well the average American understands global warming. San Diego was chosen because it draws tourists from across the United States, and would thus create a better rounded sample.

“The main concept we were hoping people would tell us, which is at the heart of understanding global warming, is that there is an asymmetry between stuff that’s coming in to our planet and stuff that’s heading out,” Ranney told Universe Today.

This asymmetry explains why sunlight (in the form of visible light) may enter the atmosphere unhindered but is later impeded by greenhouse gases (because it is no longer in the form of visible light — it has been absorbed by the Earth and emitted in the form of infrared light). But not a single person could explain global warming at this basic level.

“We were shocked at how few people knew this” Ranney said. “I thought it was a moral imperative to get the word out as fast as possible.”

So Ranney and his colleagues set out with their work in front of them, creating the videos in order to increase the average American’s understanding of global warming. Their goal is that any one of the five videos will change the lives of seven billion viewers.

“We hope that a video of 400 words or even 35 words will allow people to have a moment in time to which they fix that they knew what the mechanism of climate change was,” Ranney told Universe Today. For that single moment “their knowledge was obvious, valid, understandable and available.”

In order to drive this point home, Ranney used an analogy that began like this: “So a climate change acceptor walks into a bar.” But all jokes aside, if one who accepts anthropogenic global warming tries to convince the man sitting next to him that global warming is real, but cannot explain the physical mechanism behind global warming, then he’s in trouble. He’s likely not only lost his bar mate but encouraged a life-time of global warming denial.

We cannot expect to increase the public’s awareness and acceptance of climate change without a huge increase in scientific literacy. Even if every viewer can’t recall the exact mechanistic details of global warming they can at least say to the man sitting next to them at the bar: “Look, I can’t regurgitate it now but I did understand it then.”

This graph from NOAA shows the annual trend in average global air temperature in degrees Celsius, through December 2012. For each year, the range of uncertainty is indicated by the gray vertical bars. The blue line tracks the changes in the trend over time. Click here or on the image to enlarge. (Image courtesy NOAA's National Climatic Data Center.)
This graph from NOAA shows the annual trend in average global air temperature in degrees Celsius, through December 2012. For each year, the range of uncertainty is indicated by the gray vertical bars. The blue line tracks the changes in the trend over time. Click here or on the image to enlarge. (Image courtesy NOAA’s National Climatic Data Center.)

A second study provided college students with an explanation akin to the one found in the five-minute video.  After reading it, the students not only understood global warming better but they were also more likely to accept global warming as a reality — suggesting these videos have the power to change people’s minds.

“Eventually people come to appreciate salient evidence,” Ranney told Universe Today. “Let’s say you think you’re in a fantastic monogamous relationship. If you come home and find your partner with someone else, it only takes that one moment in time to change your belief.”

Helping people to understand the basic physics behind global warming is a vital tool in convincing them that global warming is as real as it gets. Once someone clicks on the video, the next 52 seconds alone might leave a pretty big impact.

You can view all the videos on howglobalwarmingworks.org.

Ranney emphasized help from graduate student Lee Nevo Lamprey, undergraduate student Kimberly Le and other collaborators (including Dav Clark, Daniel Reinholz, Lloyd Goldwasser, Sarah Cohen and Rachel Ranney).

Posted on by Shannon Hall

Prebiotic Molecules May Form in Exoplanet Atmospheres

Image Credit: NASA/JPL

Before there was life as we know it, there were molecules. And after many seemingly unlikely steps these molecules underwent a magnificent transition: they became complex systems with the capability to reproduce, pass along information and drive chemical reactions. But the host of steps leading up to this transition has remained one of science’s beloved mysteries.

New research suggests that the building blocks of life — prebiotic molecules — may form in the atmospheres of planets, where the dust provides a safe platform to form on and various reactions with the surrounding plasma provide enough energy necessary to create life.

“If the formation of life is like a jigsaw puzzle — a very big and complicated jigsaw puzzle — I like to imagine prebiotic molecules as some of the individual puzzle pieces,” said St. Andrews professor Dr. Craig Stark. “Putting the pieces together you form more complicated biological structures making a clearer, more recognizable picture. And when all the pieces are in place the resulting picture is life.”

We currently think prebiotic molecules form on the tiny ice grains in interstellar space. While this may seem to contradict the readily accepted belief that life in space is impossible, the surface of the grain actually provides a nice hospitable environment for life to form as it protects molecules from harmful space radiation.

“Molecules are formed on the dust surface from the adsorption of atoms and molecules from the surrounding gas,” Stark told Universe Today. “If the appropriate ingredients to make a particular molecular compound are available, and the conditions are right, you’re in business.”

By “conditions,” Stark is hinting at the second ingredient necessary: energy. The simple molecules that populate the galaxy are relatively stable; without an incredible amount of energy they won’t form new bonds. It has been thought that life could form in lightning strikes and volcanic eruptions for this very reason.

So Stark and his colleagues turned their eyes to the atmospheres of exoplanets, where dust is immersed in a plasma full of positive ions and negative electrons. Here the electrostatic interactions of dust particles with plasma may provide the high energy necessary to form prebiotic compounds.

In a plasma the dust grain will soak up the free electrons quickly, becoming negatively charged. This is because electrons are lighter, and therefore quicker, than positive ions. Once the dust grain is negatively charged it will attract a flux of positive ions, which will accelerate toward the dust particle and collide with more energy than they would in a neutral environment.

In order to test this, the authors studied an example atmosphere, which allowed them to examine the various processes that may turn the ionized gas into a plasma as well as determine if the plasma would lead to energetic enough reactions.

“As a proof of principle we looked at the sequence of chemical reactions that lead to the formation of the simplest amino acid glycine,” Stark said. Amino acids are great examples of prebiotic molecules because they are required for the formation of proteins, peptides and enzymes.

Their models showed that “the plasma ions can indeed be accelerated to sufficient energies that exceed the activation energies for the formation of formaldehyde, ammonia, hydrogen cyanide and ultimately the amino acid glycine,” Stark told Universe Today. “This may not have been possible if the plasma was absent.”

The authors demonstrated that with modest plasma temperatures, there is enough energy to form the prebiotic molecule glycine. Higher temperatures may also enable more complex reactions and therefore more intricate prebiotic molecules.

Stark and his colleagues demonstrated a viable pathway to the formation of a prebiotic molecule, and therefore life, in seemingly common conditions. While the origin of life may remain one of science’s beloved mysteries, we continue to gain a better understanding, one puzzle piece at a time.

The paper has been accepted for publication in the journal Astrobiology and is available for download here.